The present invention relates to a recording disk in which an information is recorded by electrical, magnetic and/or optical characteristic change therein caused by thermal, electrical, magnetic and/or optical energy applied to the recording disk, and a producing method therefor.
JP-A-5-212755 discloses a method for producing a substrate of a recording disk from a thermoplastic resin while controlling a temperature distribution in a molding die to obtain an evenness in thickness of the substrate in a radial direction of the recording disk.
JP-A-62-231733 discloses a method for obtaining a flat surface of a ring-shaped recording disk substrate made of a plastic material by removing simultaneously outer and inner peripheral portions of the substrate whose surfaces have relatively lower flatness.
JP-A-8-77602 discloses an optical recording medium substrate whose outer peripheral area in which an optical characteristic is deteriorated is removed to expand a recordable area radially outward on the substrate.